1. Field of the Invention
This invention relates in general to a wrench, and in particular, to a parallel, slidable and lockable jaw wrench having different head assemblies adapted for locking fasteners such as the hexagonal nut and bolt, metal plates, metal pipe or other material positioned between a particular head assembly.
2. Description of Related Art
Two typical wrenches include the adjustable wrench and the locking pliers. U.S. Pat. No. 17,531, entitled "Improved Wrench", issued on Jun. 9, 1857 to E. J. Worcester, discloses the original adjustable wrench. U.S. Pat. No. 1,489,458 entitled "Wrench", issued on Apr. 8, 1924 to W. Petersen, relates to the original locking pliers. Each of these two wrenches have existed for a considerable length of time, and many improvements to each have occurred, such as those described in U.S. Pat. Nos. 2,201,918, 3,545,315 and 3,545,316. During the period of time since the invention of these tools, each has become recognized for their own specific qualities, advantages, purposes, and shortcomings.
First, the adjustable wrench is primarily used to tighten or loosen either square or hexagon nuts or bolts. The adjustable wrench includes a body having a stationary jaw and a channel through which a moving jaw can be moved toward or away from the stationary jaw. The body also functions as a handle. Typically a toothed rack and nontraveling or captive rotatable pinion are interconnected to cause the movable jaw to move toward and away from the stationary jaw. The pinion is turned by the thumb or finger and meshes with the toothed rack on the slidable jaw to drive the slidable jaw back and forth along the rotatable pinion. Thus, the jaws are moved closer together or farther apart, depending on the rotational direction of the pinion. This type of wrench is adjustable from a fully closed position to a fully opened position by rotating the pinion. When properly adjusted, the opening will receive a hexagonal nut of any dimension that will slide between the two opened jaws.
The locking pliers is primarily used to tightly lock on objects and also includes a body having a stationary jaw and a movable jaw. The movable jaw is pivoted at the main body and rotates toward and away from the stationary jaw along an arc described by the distance from the pivot point at the main body to the end of the movable jaw. The locking pliers also has an over-center locking mechanism. The movable jaw is pivotally connected to a handle between the movable jaw's pivot point and the end of the jaw. The over-center locking rod is pivotably connected to the handle and coupled to an adjusting bolt through a spring and is located in the handle of the main body. When the adjusting bolt is rotated to move in or out of the base of the main body handle the geometry formed by the contact points of the over-center locking rod, the movable handle, and the movable jaws changes. Thus, the jaws can be locked in position since the geometry forms a fulcrum in which the over-center locking mechanism prevents jaw movement in the open direction.
However, both above-described devices lack certain features. For example, the necessary tolerances of the pinion and the rack in the adjustable type wrench facilitate easy operation, but once tightened around a nut or other fastener, those same tolerances cause "slop" or slight movement of the slidable jaw. This movement, when combined with a certain amount of torque, can result in the slidable jaw opening sufficiently to cause the wrench to slip off the nut. This slippage may cause damage to the geometry of the nut and also may tear into the surface of whatever the wrench is attached to, or may cause injury to the user. Experiences associated with these characteristics have given the adjustable wrench nicknames like "Knuckle Buster" and "Nut Wrecker", referring to banged or bruised knuckles on the human hand and damaged nut type fasteners, respectively.
Because of the possibility for slippage while using an adjustable wrench, many people have used the locking pliers in their place. U.S. Pat. No. 1,489,458 issued to Petersen teaches the working faces of the jaws of the typical locking pliers to be roughened to facilitate their gripping action when the tool is employed as a wrench. Use of the locking plier with hexagonal nut fasteners is usually associated with some type of damage to the nut since the faces of the jaws of the locking pliers do not geometrically contour with the fasteners. When sufficient force is applied to the handles of the locking pliers, enough mechanical advantage exists to cause the roughened faces of the jaws to act like a splitting wedge, thus breaking the nut, leading to the nickname of "Nut Cracker".
When the geometry of the contact between the faces of the jaws of the locking pliers and the faces of the hexagonal fasteners is examined in close detail, it becomes obvious that very poor surface contact results. This is due to shape of the faces, aggravated by the way in which the jaws are brought closer together. The movable jaw in the locking pliers is brought closer to the stationary jaw by angular rotation. The faces of the movable jaw and the stationary jaw are parallel to each other at only a single point in the arc of rotation of the movable jaw. At this point, the distance between the faces of the jaws is fixed, and although the jaws are parallel at this point, the roughened faces will provide very poor surface contact with a nut that fits exactly between the faces. Further, some slippage or damage to the fastener can occur even under these conditions where the jaw faces are parallel with the faces of the fasteners. At any other position along the arc, the jaw faces are nonparallel, and thus cannot provide the geometry necessary to grip hexagonal or square nut fasteners correctly. Moreover, both wrenches have jaws that are fixed configurations and do not facilitate the gripping of various other objects.
Whatever the merits of the prior wrenches, they do not achieve the benefits of the present invention.